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I have a 2004 400ex with Two Brothers Slip on exhaust, dynojet CDI, Hot Cams Stage II. I still have the stock jet in it which are 148 main and 38 pilot jet I haven't rode it yet and I am wondering what the main and pilots should be. any help would be appreciated.

I have a 2004 400ex with Two Brothers Slip on exhaust, dynojet CDI, Hot Cams Stage II. I still have the stock jet in it which are 148 main and 38 pilot jet I haven't rode it yet and I am wondering what the main and pilots should be. any help would be appreciated.

Airbox lid on or off and elevation play a big part. I'll assume below 3000 feet.

If i remember you can get away without changing the pilot but, a 42 will make her start much easier and pretty much eliminate the need for a choke. It's been a while but, I believe a good place to start would be a 155-160 main if you have the lid on. With it off I'd jump to 170ish and watch it. May need to go higher. It's always better to go to big than go too little. Those are numbers for kehien. DJ sizes are different. I think with lid off and full exhaust they recommended a 170 which is like 190 something Keihien.

Oh, and 3 turns out on fuel screw.

Tip: Buy individual jets. The DJ kit is expensive and you can get individuals for a few bucks a piece.

Stock bore and compression? Stock filter? I run a 158 with exhaust filter and 85.5mm 10:1 piston. 190 is way to big for exhaust and lid off. Deffinatly go with the 42 pilot for now you may want to try out a 45 or higher depending o you bore and compression. I would start in the 160-170 range you may have to go higher jetting is so individual you may have to try a couple to get were you like it. Buy the keihin jets, almost anywere will carry them. Also if its your first time tearing the carb apart I reccomend changing the hardware stock come with cheap brass ones that strip like crazy and you will damage them taking them out anyways so be prepared to get frustrated I just use vice grips to get them out if you strip them to bad. Check out www.exriders.com there are thousands of posts on jetting questions it will help you to get a better idea on were you need to start. The guys in the 400ex section are top notch.

I checked and sure enough it's what they recommend though. Maybe has something to do with the clip adjustment? I had the dj160 first and it was to lean. Okay when lid on but, when removed it was not good. dj170 was pretty much dead on.

..every quad is different and there are so many factors needed to get jeffing correct. DJ kit reccomends using there needle and clip which I think is not nessicary at all the stock is more than sufficient. ..

I agree. I did not use the DJ needle. Mostly because I couldn't get mine out but, I doubt I would of seen enough change to make a difference for me.

You can get pops and backfires if your jetting is too rich also. Never assume your jetting is automatically lean if it pops or backfires a little. I wont have any popping or backfireing for a week or two then it will start doing it. I clean my airfilter and it goes away.
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None of your posts are realitive to the op's topic why don't you take a hike. Where did he ask if his quad had revers eor were did he ask about backfires or poping. Yeah some exhaust will pop even if the pilot circut and jets are set up correctly. However other factors will help determine if it is, and if you are to rich or to lean.

None of your posts are realitive to the op's topic why don't you take a hike. Where did he ask if his quad had revers eor were did he ask about backfires or poping. Yeah some exhaust will pop even if the pilot circut and jets are set up correctly. However other factors will help determine if it is, and if you are to rich or to lean.

Going back and deleting ALL of his posts. He won't be back under that name.

If you see any posts like his that are vague at best, and have a link in their signature that is advertising, send the mods a note.